The present invention relates to a valve actuator for controlling the position of a flow-control valve positioned within a passageway to regulate fluid flow through the passageway, and particularly to valve actuators for achieving highly precise regulation of fluid flow. More particularly, the present invention relates to high precision electromechanical actuators for control of fluid flow through a valve of the type used to regulate air or fuel flow into a combustion chamber in an industrial burner.
Combustible air and fuel mixtures are typically burned in industrial burners to produce heat of the type often needed in industrial applications. Burner control systems typically regulate the flow of air and fuel to a burner using flow-control valves provided in the air and fuel supply pipes that are arranged to supply air (or oxygen) and fuel to the burner.
Industrial burner applications impose a variety of performance requirements on a valve actuation system included in a burner control system. For example, certain industrial heating processes require highly precise control of the air and fuel flows, which dictates that a valve actuator used in a burner control system must be able to position the flow-control valve very accurately to regulate fluid flow past the valve. Furthermore, the ability to regulate fluid flow precisely can be complicated by changing environmental parameters, such as fluctuations in the pressure and temperature of the air and fuel supplies.
In practice, operators of industrial burner systems often need to maintain or upgrade the performance of the burner system. This can be accomplished by repairing or replacing either the entire burner control system or only a portion of the control system, such as a valve actuator component.
According to the present invention, a valve actuator assembly is provided for positioning a flow-control valve member positioned to lie in a flow path of a fluid supply system. The valve actuator assembly includes a housing, a driver coupled to the housing, and a controller. The driver the includes a motor and a shaft connected to the motor and configured to move the flow-control valve member from an actual valve position to a desired valve position to regulate the flow of fluid through the flow path. The controller is coupled to the motor and configured to command the motor to position the flow-control valve member in the desired valve position. The controller includes a control module and a sensor. The control module is programmed to receive a position command and to instruct the motor to move the valve to the desired valve position based on the position command.
The sensor is coupled to the control module and the shaft to indicate the actual valve position of the flow-control valve member using a valve position signal generated by the sensor and sent to the control module. The control module is programmed to receive and compare the valve position signal received from the sensor to calibration parameters to determine whether the valve is in the desired valve position and, if necessary, to instruct the motor to reposition the flow-control valve member in the desired valve position.
In preferred embodiments, the control module is configured to store sensor specific calibration parameters and to instruct the motor to move the flow-control valve member to the desired valve position. The control module is programmed to compare the valve position signal from the sensor to the sensor specific calibration parameters to determine whether the valve is in the desired valve position and, if necessary, to instruct the motor to reposition the flow-control valve member in the desired position.
The controller includes a network interface coupled to the control module and configured to communicate with a communications network. The control module is programmed to receive position commands through the network interface from the communications network to instruct the driver to move the flow-control valve member to the desired valve position.
A method is provided for calibrating the valve actuator assembly. The method includes the step of providing a valve actuator assembly having a driver connected to a flow-control valve member and a controller coupled to the driver. The controller includes a control module coupled to the driver and a sensor coupled to the control module. The control module is configured to command the driver to move the flow-control valve member to a desired valve position. The sensor is configured to indicate an actual valve position using a valve position signal indicative of the actual valve position. The method further includes the steps of generating calibration parameters specific to the sensor, commanding the driver to move the flow-control valve member to a desired valve position, generating a valve position signal, comparing the valve position signal with the calibration parameters to determine the need to reposition the valve, and commanding the driver to reposition the flow-control valve member to the desired valve position.
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.